What is a Carbon Footprint?

You hear a lot of talk these days about "carbon footprints". But what is a carbon footprint, anyway?

Carbon dioxide (CO2), while not the only greenhouse gas, is the most abundant. CO2 is emitted into the atmosphere when we burn fossil fuels, and most of the energy in this country comes from burning fossil fuels. Thus, anything that requires energy to manufacture, transport, or operate causes the emission of CO2 (see my previous post, The Carbon Footprint of… Everything).

A "carbon footprint" is the amount of CO2 released by an activity or entity. So what's your carbon footprint?

It's difficult to make an exact calculation because the carbon footprint of so many things is unknown – for example, the amount of CO2 emitted in the manufacturing of your shoes. But the basics are known, and can give a very good picture of how your choices contribute to global warming. The kind of home you live in, how much you drive, and how often you fly can account for half a person's carbon footprint.

You can calculate your carbon footprint for these three main elements on our Web site. You enter basic information about your lifestyle, and we take it from there. After the calculation, the site describes how you can minimize or offset your emissions – smart heating and cooling, smart use of appliances, smart driving, switching to compact fluorescent light bulbs, and selecting offsets.

Here are some statistics to think about:

  • The average American car emits seven tons of CO2 per year.
  • The average American person emits 20 tons of CO2 per year.
  • The United States emits 7 billion tons of CO2 per year.
  • The world emits 30 billion tons of CO2 per year.

If you're confused by the notion that gases like CO2 have weight, check out my earlier post Picturing a Ton of CO2.

This entry was posted in Economics, Greenhouse Gas Emissions. Bookmark the permalink. Both comments and trackbacks are currently closed.

7 Comments

  1. davemcarthur
    Posted May 12, 2007 at 8:31 pm | Permalink

    Hello Bill
    You write
    Carbon dioxide (CO2), while not the only greenhouse gas, is the most abundant.

    While we can be considered Carbon Beings we are far more sensitive to the fact that we are Water Beings- we are most sensitive to changes in the water content of our environment. Water vapour is our dominant experience of climate change(weather) Water Vapour is also by far the dominant warming trace gas and is responsible for over 20C of the atmospheric warming effect. What science underpins your communication that carbon dioxide is the most abundant of the Warmer Trace Gases? I fail to find the sense in excluding it from discussion about the thermodynamics of Earth's surface. I suggest this omission constitutes a massive block to the popular understanding of climate processes.

    kia ora – go well

    Dave McArthur

  2. youre_only_hope
    Posted May 13, 2007 at 2:49 pm | Permalink

    true, carbon dioxide is not the only greenhouse gas, but it is not true that it is the most abundant. If you have done any research beyond what Al Gore has told you, you would know that water vapor is the most abundant (see chart) nearly making up 95% of the total greenhouse gases. If you look at the link in the last sentence, you can also see that CO2 makes up only about 3% of the total greenhouse gases with only .117% of that coming from humans. I find it hilarious that you self proclaimed "Experts" on global warming tell us that the amount of human released CO2 is changing the climate of the entire globe, yet if you look at how much CO2 is released naturally ( volcanoes alone release 165 gigatons of CO2 compared to 6.5 by humans) you would think that if you were truely concerened about our climate, you would try and reduce the amount of CO2 releaced naturally instead of trying to regualte the ones who are not the biggest offenders. Expanding on my first point of Co2 not being the most abundant greenhouse gas, I also find it funny that people are saying that releasing greenhouse gases is what is causing global warming but if anyone thesedays used common sense instead of just following some ideology that one person says is true, people would soon realize that if you release greenhouse gasses into the air, you are actually releasing mostly water vapor into the atmosphere. Now seeng as clouds are made from water vapor, the increased…

  3. youre_only_hope
    Posted May 13, 2007 at 2:54 pm | Permalink

    amounts of water vapor in the atmosphere due to the emmissions of greenhouse gases would lead to an increase of the amount of clouds in the sky. With an increased amount of clouds (which are white, and as everyone knows he color white is great at reflecting light and heat) less sun would be able to penetrate the atmosphere, absorbe into the earth, and return to the atmosphere warmer that it origionally came. This is what is funny, when you just use common sense, you can prove that greenhouse gases are not causing the recent warming of the globe, something else is. The SUN!

  4. Posted May 14, 2007 at 2:21 pm | Permalink

    Yes, water vapor is more abundant than carbon dioxide, but it's not relevant to the global warming problem. For why, see my post on "The Water Vapor Fallacy"

  5. Posted May 14, 2007 at 3:33 pm | Permalink
  6. K.C. Weber
    Posted May 15, 2007 at 7:21 pm | Permalink

    In response to the above comments from youre_only_hope and Dr. Chameides’ comment that global warming is not caused by changes in the sun, I would like to talk about the importance of the sun in a discussion on global warming.

    First of all, the sun is the largest body in our solar system, several times larger than the largest planet, Jupiter, and many, many times larger than the Earth. Not only is its gravity holding all the planets, asteroids, and comets in orbit, but various forms of its energy constantly go to the farthest reaches of the solar system.

    I’m not sure how much the sun contributes to global warming, but we can’t be blind and say that it has no effect on the planet’s temperature. If there was no effect, there would be no life on Earth. Visitors to Alaska can see an example of the sun’s energy interacting with the Earth when they see the Northern Lights. This is radiation from the sun interacting with the Earth’s magnetic field around the poles. Another example is when there are strong solar flares on the sun’s surface. At times like this there are often interruptions in the Earth’s communications and electrical power. If an astronaut were in orbit during a time of increased solar activity, the radiation would be dangerous to him.

    Earth and all the planets are constantly hit by many forms of solar energy, and we are still learning which of them causes variations in a planet’s temperature and climate. In my study of science, I have come to the conclusion that the sun is affecting the Earth and other planets in ways we have not yet discovered yet.

    Now, my love of science has made me an optimist. The more I learn, the more I realize how fantastic our universe is. It causes me to often see things in very positive ways. In environmental talk, I often hear of all that we need to give up and do without. I have a different viewpoint, however. In my opinion, the do without mentality is no good. We need to think of what we can do to improve our lifestyle not take away from it. Rather than denying that the sun has anything to do with global warming, let’s learn how to tap the sun’s variety of energies in ways that we haven’t imagined yet. Or go the other direction. There is untapped energy at the Earth’s core if we could learn how to tap it.

  7. K.C. Weber
    Posted May 15, 2007 at 7:24 pm | Permalink

    Now, even though I do not feel that our use of carbon based fuel is the main cause of global warming, I feel its use is becoming somewhat ancient. Rather than saying we should do without, let’s take positive action to bring our world up to speed and make it a better place where we will have more energy to live on, not less.

    Sincerely,
    K.C. Weber

5 Trackbacks

  • [...] Which emissions do you count? For the Yahoo! calculator, we focused on emissions from home energy use, personal driving, and commercial aviation. We could make solid estimates of average emissions from these activities, and there are easy steps individuals can take to reduce those emissions. These three activities account for 9.4 tons of CO2 per person per year, which is about half of the total CO2 emissions per person in the U.S. Some people also refer to the emissions attributable to a person as his/her carbon footprint. How do you count those emissions? Greenhouse gas emissions are often higher when you consider gases other than CO2, but non-CO2 emissions can be difficult to calculate. Many carbon calculators ignore all non-CO2 emissions. The Yahoo! calculator includes non-CO2 gases for flying and dietary choices. How much information from the user? The more information I have, the better job I can do calculating your baseline emissions and your savings. What's your current average annual electricity consumption? What state do you live in? How long do you keep each of your light bulbs on every day? What make and model are your appliances? Obviously that approach can get ridiculously cumbersome to users. So instead we often use national averages. Do you include regional differences? Some factors, such as the amount of CO2 emitted per kilowatt-hour of electricity, vary enormously from state to state. The national average emissions rate is 1.34 pounds of CO2 per kWh. But in North Dakota it's 2.24, and in Vermont it's a clean 0.03! We accounted for these differences in our calculators on http://www.fightglobalwarming.com; Yahoo! uses the national average. [...]

  • [...] Which emissions do you count? For the Yahoo! calculator, we focused on emissions from home energy use, personal driving, and commercial aviation. We could make solid estimates of average emissions from these activities, and there are easy steps individuals can take to reduce those emissions. These three activities account for 9.4 tons of CO2 per person per year, which is about half of the total CO2 emissions per person in the U.S. Some people also refer to the emissions attributable to a person as his/her carbon footprint. [...]

  • [...] Power Profiler – Most carbon footprint calculators, including ours, rely on averages to estimate your carbon footprint. But you can get a [...]

  • [...] Belkin's Conserve Surge Protector – At the Consumer Electronics Show this month, Belkin showed a new surge protector called Conserve that can shut off six of its eight outlets with a switch, or with a handy remote control (in case you don't like climbing under your desk). Standby or "phantom" power from devices such as TVs, computers, and battery chargers, can account for up to 20 percent of your electric bill. This device could save you money, as well as reduce your carbon footprint. [...]

  • [...] for transportation by walking and biking gives you the best kind of exercise, and also reduces your carbon footprint. Drinking tap water rather than bottled gives you clean water at one-thousandth the [...]

  • About this blog

    Expert to expert commentary on the science, law and economics of climate change.

  • Get blog posts by email

    Subscribe via RSS

  • Meet The Bloggers

    Megan CeronskyMegan Ceronsky
    Attorney

    Nat KeohaneNat Keohane
    Vice President for International Climate

    Ilissa Ocko
    High Meadows Fellow, Office of Chief Scientist

    Peter Zalzal
    Staff Attorney

    Gernot Wagner
    Senior Economist

    Graham McCahan
    Attorney

    Mandy Warner
    Climate & Air Policy Specialist

    Pamela Campos
    Attorney

    Kritee
    High Meadows Scientist

  • Posts by topic

  • Archives